The crystal structure of the feldspathoid panunzite (natural tetrakalsilite) was solved and refined to an R index value of 0.078, for 1753 independent reflections collected with Zr-filtered MoK-alpha radiation. Panunzite is hexagonal, space group P63, with a = 20.496(5), c = 8.549(3) Å. The crystal structure is a stuffed derivative of tridymite, and is characterized by six-membered tetrahedral rings, which are present in oval, ditrigonal and nearly hexagonal conformations. The rings are built up by regularly alternating SiO4 and AlO4 tetrahedra. In the cavities of the framework sodium and potassium cations find location. Some analogies between panunzite and nepheline frameworks were observed.
|Autori:||MERLINO S; FRANCO E; MATTIA CA; PASERO M; DE GENNARO M|
|Titolo:||The crystal structure of panunzite (natural tetrakalsilite)|
|Anno del prodotto:||1985|
|Appare nelle tipologie:||1.1 Articolo in rivista|